One of the first things you may notice about these pictures is that they appear to show a regular 5 Series. Gone are all the tell-tale signs of the 5 Series ActiveHybrid Concept that debuted in Geneva, including the propeller wheels and revised lower front fascia. How do we know this is a hybrid prototype then? A clue hiding in plain sight on the trunk lid. See that sticker that says “RESCUE Remove in case of emergency”? The last time we saw one of those, it was on the back of an X6 ActiveHybrid prototype.

The BMW 5 Series ActiveHybrid uses the same underlying technology as the X6 and 7 Series ActiveHybrids, but with a different engine. While the 7 Series and X6 mount a turbocharged V-8 to the electric motor, the 5 Series ActiveHybrid instead uses BMW‘s latest turbocharged inline-six, a 3.0-liter mill with direct injection and a twin-scroll turbocharger good for 300 horsepower and 300 pound-feet of torque. Sandwiched between the engine and eight-speed automatic transmission is a 40 kW electric motor that can propel the car at low speeds on its own, supplement the gasoline engine, or act as a generator to recover energy during braking. BMW says the system is good for a 10-percent reduction in fuel consumption and emissions.